Most desk chairs with a relatively simple structure have a backrest immovably connected to a seat. That is, the backrest is not adjustable relative to the seat, and therefore might not be able to comfortably support a user's back. Some desk chairs are improved by pivotally connecting the backrest to the seat and providing at the pivotal connection with an elastic element to support the backrest, so that the backrest is allowed to elastically swing rearward when a force is applied to the backrest. This type of backrest functions like a rocking chair to support the user's back, and is more comfortable for use. However, the backrest could not always support the users' back at a most suitable position due to different figures of users. For some relatively high or short users, the backrest of a general desk chair usually does not provide good support to the back and waist. There are developed some chairs with the backrest and the seat thereof being independently adjustable. However, the user has to leave the seat to operate the chair and achieve the purpose of adjustment. This is of course inconvenient for the user to do so.
It is therefore tried by the inventor to develop a backrest adjusting mechanism to overcome the drawbacks existed in the conventional chairs.